摘要
银河系自转曲线研究有着重要的天体物理意义。自转曲线可以利用多种星族I示踪天体来加以测定,如经典造父变星、行星状星云、碳星、疏散星团、OB型星,以及中性氢巡天等。相关研宄表明,在太阳圈之外,银河系自转曲线大致保持为平坦状,甚至略有抬高,从而为大质量暗晕的存在提供了有力的观测证据。
Measuring the Galactic rotation curve is of fundamental importance for solving a number of astrophysical problems, such as estimating the total mass of the Galaxy, determining the distribution of matter, exploring dark mater, studying the dynamics of the Galaxy and its subsystems, etc. Since 1930s the data on various kinds of population I objects as tracers have been used to determine the Galactic rotation curve, including classical Cepheids, planetary nebulae, C stars, young open clusters, OB stars, HI survey etc., and in many studies more than one kind of the above disk objects are synthetically used. With observational data accumulating, bigger and bigger samples of population I tracers have been used to determine the Galactic rotation curve. There are two different cases and methods for rotation curve determination. For the inner Galaxy（R 〈 Re）, it follows that the radial velocity components in a given direction reach a maximum in the point nearest to the galactic center, and the circular velocities can be easily found even with distances of tracers from the Sun being unknown, which is called as the tangential point method. For the outer Galaxy（//. 〉_ RQ）, both radial velocities and heliocentric distances of tracers must be independently measured in order to determine their circular velocities. By the end of the 20th century and later, in addition to radial velocities, proper motion data are also used for rotation curve studies. So far as HI survey data are concerned, some different approaches are used to explore the Galactic rotation curve, for instance, from changes of tile thickness of the HI layers with different heliocentric distances. Up to now, it is consistently shown from almost all of different studies on the Galactic rotation curve from different tracers that the rotation curve of the outer Galaxy is roughly flat or appears to rise slightly from the Sun＇s location to the heliocentric distance of 20 kpc. On the other side, from a recent study on the kinematics of the SDSS data the circular velocity curve is found to be gradually falling from 220 km.s-1 at the Sun＇s location to some 175 km.s-1 to the heliocentric distance of 60 kpc. Besides what mentioned above, some issues concerned with the rotation curve determi- nation of the Galaxy are also briefly discussed, such as introducing higher order terms into the Oort＇s formulae, expressing or describing the rotation curve with analysis functions or the mass models of the Galaxy, local Galactic parameters, K-effect or non-axial symmetric movements, and vertical gradients of circular velocities.
出处
《天文学进展》
CSCD
北大核心
2012年第4期487-500,共14页
Progress In Astronomy
基金
国家自然科学基金(10773020
10778003
10833055)
